Search Results (252)

Aeolian processes in deserts endanger railway infrastructure through sand burial and abrasion. Conventional railway route-selection methodologies, however, predominantly rely on qualitative expert judgements and overlook the physical wind-sand dynamics. To overcome this gap, we develop a quantitative assessment framework for railway embankment versus bridge configurations, grounded in aeolian physics and explicitly designed to capture the directional and energetic characteristics of sand-transporting winds. We used ERA5-Land reanalysis wind data (2001–2020) to calculate resultant drift potential (RDP), wind directional variability (WDV), and their inter-annual trends. These aeolian parameters were converted into a look-up-table scoring framework, which captures the contrasting vulnerabilities of embankment and bridge structures. Our global-scale assessment reveals that railway embankment generally achieve higher suitability scores (2–24) across most deserts, whereas bridges exhibit localized advantages (scores 9–12) in regions with intense and unidirectional sand flux, particularly in northern and western China. Beyond engineering decision-making, the scoring outputs also serve as a first-order indicator for identifying areas where railway construction may minimally disturb natural wind-sand processes. This physically-based framework compensates for the lack of quantitative atmospheric forcing parameters in traditional planning, offering a practical tool for structural selection and a reference for long-term hazard mitigation under changing climate. Full article

Microbially induced calcium carbonate precipitation (MICP) is influenced by the physiological response of ureolytic bacteria to local environmental backgrounds. This liquid-culture process-screening study examined responses of Sporosarcina pasteurii ATCC 11859 under combined alkaline–low-NaCl backgrounds and elevated temperatures relevant to inland aeolian-sand environments. Cultures were sequentially exposed to five pH-NaCl backgrounds at 30 °C, followed by temperature treatments (35–41 °C) under three selected backgrounds. Cell density (OD₆₀₀), urease activity, and apparent dry precipitate mass (ADPM), used as an operational dry-residue endpoint, were measured. Temperature, pH–NaCl background, and their interaction significantly affected urease activity and OD₆₀₀, whereas ADPM showed a significant temperature effect but was not interpreted as quantitative CaCO₃ production. A composite analysis indicated that pH 9.3, 1.4‰ NaCl and 35–37 °C represented a coordinated liquid-culture response range. At pH 9.3, 1.4‰ NaCl, and 37 °C, urease activity, OD₆₀₀, and ADPM were 1.155 mM urea min⁻¹, 1.662, and 1.14 g, respectively. Overall, the identified range provides a practical liquid-culture basis for subsequent sand-tray stabilization tests under aeolian-sand conditions. Full article

Cement-improved aeolian sand is a potentially sustainable geomaterial that has been used in engineering applications such as subgrade filling and slope stabilization in cold regions. To investigate the degradation patterns of the dynamic mechanical properties of improved aeolian sand following freeze–thaw cycles, this study conducted the Split Hopkinson Pressure Bar (SHPB) test on cement-improved aeolian sand under different freeze–thaw cycle numbers and cement content, revealing its dynamic mechanical characteristics, energy dissipation patterns, and failure mechanisms. The results indicate that, as the number of freeze–thaw cycles increased, internal microcracks progressively develop and propagate, and the dynamic mechanical properties of the modified soil gradually deteriorate. This is manifested by a gradual decrease in the dynamic peak stress, a decline in the dissipated energy density, and an upward trend in the fractal dimension of the fragment mass. Compared to the deterioration observed during the first ten freeze–thaw cycles, the magnitude of the changes in dynamic mechanical parameters decreased, indicating a gradual reduction in the overall rate of deterioration. The addition of cement enhances the frost resistance of the modified soil; however, an excessively high cement content shifted the failure mode toward brittle fracture. and the fractal dimension exhibits a decreasing trend. The conclusions of this study offer a theoretical framework for catastrophe mitigation in cement-improved aeolian sand, including freeze–thaw and dynamic loading. Full article

Desert highways have long been subjected to aeolian sand hazards, and sand accumulation on the pavement significantly weakens the surface texture and deteriorates skid resistance, which has become one of the core contributing factors to traffic accidents on desert road sections. Current research predominantly focuses on the attenuation law of the macroscopic friction coefficient of sand-covered pavements; however, the quantitative correlation mechanism between three-dimensional micro-texture characteristics and skid resistance has not been sufficiently revealed, and there is a lack of high-precision skid resistance prediction methods under multi-condition coupling scenarios. To address the above research deficiencies, this paper takes the asphalt pavement in the Tengger Desert region as the research object. A handheld three-dimensional texture scanning system was employed to acquire the three-dimensional pavement morphology parameters under different sand coverages, and the sideway force coefficient (SFC) was synchronously measured under the corresponding conditions. Through Pearson correlation analysis and dual multiple comparison correction using the FDR-BH and Bonferroni methods, the core influencing indicators were identified. Subsequently, a skid resistance prediction model based on a BP neural network optimized by the particle swarm optimization (PSO) algorithm was constructed and horizontally compared and validated with LSTM and PSO-SVM models. The research results show the following: ① under dry conditions, the root mean square height ($S_q$), peak density ($S_{pd}$), arithmetic mean peak curvature ($S_{pc}$), valley void volume ($V_{vv}$), root mean square slope ($S_{dq}$), and developed interfacial area ratio ($S_{dr}$) are significantly linearly correlated with the SFC, among which $S_q$, $S_{pd}$, $S_{pc}$, and $V_{vv}$ are the core controlling indicators, with the absolute values of their correlation coefficients all exceeding 0.73, and ② the constructed PSO-BP prediction model achieved a coefficient of determination $R^2$ of 0.86093 on the test set, and its prediction accuracy and generalization ability are both superior to those of the LSTM and PSO-SVM models, enabling it to effectively characterize the nonlinear mapping relationship between multiple texture parameters and skid resistance. This study can provide theoretical support and a technical basis for skid resistance evaluation, sand accumulation disaster warning, and scientific maintenance decision-making for desert highways. Full article

Coastal dune fields provide important ecological and geomorphic functions, while their evolution is strongly influenced by groundwater-controlled surface moisture. However, the effects of seasonal groundwater-level fluctuations and moisture-affected sand on long-term dune development remain insufficiently represented in numerical models. In this paper, a time-varying groundwater-level field and moisture-dependent entrainment thresholds are incorporated into a real-space cellular automaton model to investigate the coupled evolution of coastal dunes and interdune lakes. The results show that rising groundwater levels reduce the wind-erodible surface area, inundate interdune depressions, and delay the growth of peak dune height. Periodic water-level fluctuations also produce a sediment storage–release cycle, in which sand is temporarily stored on inundated interdune surfaces during high-water stages and is progressively remobilized during subsequent low-water stages, while newly exposed moisture-affected sand remains subject to an elevated entrainment threshold. In addition, increasing the critical threshold shear stress within the groundwater-controlled moisture-affected layer suppresses dune development and reduces final peak dune height by approximately 8–17%. Comparison with the observed wet-season water-pond area further shows that incorporating the moisture-affected layer brings the simulated relative water-pond area closer to the observed value in the Lençóis Maranhenses dune field. Overall, the results demonstrate that groundwater regulates dune evolution through both direct inundation and an enhanced entrainment resistance of moisture-affected sand above the water table. Full article

The formation and disappearance of paleolakes are sensitive indicators of environmental evolution in arid and semi-arid regions. Their disappearance records comprehensive information on regional hydrological conditions, climatic changes, and tectonic activities, thereby offering unique research value for elucidating the environmental driving mechanisms behind water resource changes in historical human settlements and the concomitant rise and fall of civilizations. This study analyzed the contact interface between extensively distributed lacustrine deposits and the overlying aeolian dune sands around Tongwan City using optically stimulated luminescence (OSL), and combined with relevant documentary evidence to elucidate the relationship between paleolake disappearance and the abandonment of the ancient city. The OSL dating results demonstrated that the disappearance of paleolakes and the initiation of desertification around Tongwan City were mainly concentrated between about 1200 and 900 years before present, closely corresponding to the abandonment of Tongwan City in AD 994. Field investigations additionally revealed that well-developed fluvial erosion surfaces are pervasively present at the top of lacustrine deposits around Tongwan City, while multiple fluvial terraces are exposed along the Wuding River. These features collectively indicate that regional crustal uplift event led to fluvial incision. The results indicated that the abandonment of Tongwan City was not attributable solely to climatic aridification, but instead resulted from the combined influences of favorable hydrothermal conditions during the High-Temperature Period of the Northern Song (HTNS, AD 994–1094) and regional tectonic uplift. Tectonic uplift facilitated deep incision of the Wuding River valley, while increased precipitation during the warm period enhanced surface water infiltration and drainage, resulting in a significant decline in groundwater levels, the disappearance of paleolakes, and ultimately the depletion of water resources upon which the ancient city relied. These findings provide new evidence from an environmental geological perspective and present a key scientific explanation for the paradox that Tongwan City was abandoned during a relatively warm climatic interval. Furthermore, the coupled mechanism of tectonic uplift, fluvial incision, sharp groundwater decline, and societal collapse revealed in this study not only provides a valuable reference for investigating the abandonment of ancient cities in arid and semi-arid regions during historical periods, but also offers important implications for assessing water resource vulnerability of ancient settlements on analogous geomorphic units under global climate change, and may serve as a geological–historical warning and reference for water security management in human habitations under current and future warm-climate conditions. Full article

The surface soil in the Shendong mining area is dominated by aeolian sand and sandy sediment, while precipitation is limited, and evaporation is intense. Under these conditions, shallow reconstructed soil has difficulty retaining plant-available water, which constrains vegetation restoration. This study evaluated how low-range increases in fine-particle clay content affect both water retention and upward water conduction in sandy reconstructed soil. Sandy material from the Shangwan mining area and exogenous river clay were mixed into four treatments, and soil water characteristic curves (SWCCs) were determined by centrifuge over 10–1000 kPa matric suction. The data were fitted with the Van Genuchten model and combined with capillary-rise tests. The results showed that increasing fine-particle content shifted the SWCC upward and raised both saturated and residual volumetric water contents. SN10 reached 17.18% and 5.55% volumetric water content at 10 and 1000 kPa, respectively, and its effective water capacity in the 33–1500 kPa range was 17.9% higher than that of ST. At the same time, fine-particle enrichment in the bottom layer reduced wetting-front rise during capillary testing, indicating a trade-off between water storage and upward replenishment. Within the tested fine-particle range, moderate clay addition improved the hydraulic performance of sandy reconstructed soil, but soil design should balance precipitation retention, infiltration, and capillary supply. Because each treatment and soil-column configuration was represented by only one independently prepared experimental unit, experimental variability and reproducibility could not be evaluated. This study should therefore be regarded as a preliminary and exploratory laboratory assessment conducted under a specific set of material-preparation procedures, specimen geometries, and boundary conditions. The results describe specimen-level hydraulic contrasts rather than reproducible treatment effects and should not be directly generalized to field-scale soil reconstruction. They support a preliminary hypothesis for future replicated testing: fine-particle enrichment may increase water retention while slowing upward capillary replenishment. Full article

High-volume fly ash binder and aeolian sand have been widely used in the production of low-carbon ultra-high performance concrete (UHPC) owing to their environmental and economic benefits. However, such low-carbon UHPC still faces the volume stability issues, including autogenous shrinkage, drying shrinkage and early-age cracking. In this study, a superabsorbent polymer (SAP) was incorporated into low-carbon UHPC containing high-volume fly ash and aeolian sand to improve its volume stability through internal curing. The effects of SAP particle size and dosage on the mechanical properties and volume stability of low-carbon UHPC were investigated. Results showed that the addition of 0.3% SAP with a particle size of 180–600 μm significantly reduced shrinkage and early-age cracking while maintaining the compressive strength. Furthermore, the microstructure of low-carbon UHPC was characterized using advanced techniques to shed light on the underlying mechanisms. Full article

In arid and hyper-arid regions, the temporal dynamics of surface soil moisture (SSM) significantly affect surface erodibility, as well as aeolian sediment transport and deposition processes. Conventional measurement techniques fail to meet the requirements of fine spatiotemporal resolution monitoring, and terrestrial laser scanning (TLS) possesses unique advantages and great application potential for SSM detection. In this study, the accuracy and feasibility of TLS for retrieving SSM in sandy desert were evaluated. The experimental results reveal that sand particle size, measurement distance and SSM are three important factors affecting laser signal amplitude. The relationship between measurement distance and amplitude follows a three-stage variation pattern that can be well fitted by an exponential decay model. Amplitude fluctuates with sand particle size, and the fluctuations become more pronounced at longer measurement distances or higher SSM levels. A strong linear correlation exists between amplitude and SSM within the range of 2.5–20%. Accordingly, particle size-dependent calibration equations were established to estimate SSM from TLS observations. Field validation was further conducted to clarify the applicable scope and constraints of this method. This approach provides an innovative solution for the high-precision, rapid, non-contact and dynamic monitoring of SSM in arid sandy desert. Full article

Sandy desert ecosystems of Central Asia are highly vulnerable to climate change, land degradation, and increasing anthropogenic pressure, yet the soil conditions supporting native desert vegetation remain insufficiently characterized. This study investigates soil development and physicochemical properties under the canopy of Calligonum aphyllum across different geomorphological conditions in the southern Balkhash region of Kazakhstan. Field investigations were conducted within the Ili River delta, where nine soil profiles were described across three geomorphological settings. Soil samples were analyzed using standard soil analytical methods to assess particle-size composition, soil organic matter, nutrient availability, carbonate content, salinity, and sodicity indicators. The studied soils were predominantly sandy, with sand fractions ranging from 88 to 96% and very low clay content, resulting in weak horizon differentiation, high permeability, and limited water-retention capacity. Soil organic matter and total nitrogen contents were consistently low across all sites. Available phosphorus decreased with depth, particularly in carbonate-enriched horizons, whereas exchangeable potassium remained comparatively high. Total salinity was low, with chloride–sulfate and calcium–sodium dominance, and no evidence of sodicity was observed based on SAR values. Clear differences among geomorphological settings were identified, including relatively homogeneous sandy substrates, dust-enriched semi-stabilized sands, and actively reworked aeolian ridges. The results indicate that C. aphyllum can persist under nutrient-poor, coarse-textured sandy conditions and is associated with surface root concentration, local substrate stabilization, and early soil-profile differentiation. These findings highlight the ecological importance of C. aphyllum in sandy desert habitats and provide site-specific soil information relevant to vegetation-based restoration and sustainable land management in arid regions of Central Asia. Full article

Currently, existing studies primarily perform damage simulations based on random aggregate mesoscale models of concrete. In contrast, research on freeze–thaw numerical simulations based on realistic concrete mesostructural models remains relatively scarce. In this study, based on X-ray computed tomography (CT) scanning technology, the influence of freeze–thaw action on the pore structure evolution law of aeolian sand self-compacting concrete (ASSCC) was analyzed. Mesoscale characteristics of the mortar, aggregates, and pores were extracted using image processing software, and a realistic mesostructural model of ASSCC was subsequently established. Furthermore, numerical simulations of the freeze–thaw cycle process were conducted using the finite element software ABAQUS. The results indicated that during the initial freeze–thaw stage, the formation of small new pores predominated within the concrete. As the freezing and thawing cycles progressed, these pores gradually interconnected and coalesced into larger irregular pores, which eventually led to the development of penetrating cracks that resulted in structural failure of the ASSCC. The mesostructural model derived from CT data effectively simulated the failure patterns and mechanical performance of ASSCC under both uniaxial compression and freeze–thaw conditions. This provides an effective means for predicting the mechanical properties of concrete under freeze–thaw cycling conditions. Full article

An aeolian event and a fluvial episode affected Gale crater, Mars, prior to 3.6 billion years ago. Both were short-lived and catastrophic. The same two events also modified the Southern Highlands of the red planet during the same time interval. We show that events in Gale crater were a part of those that modified vast areas of the southern hemisphere of Mars. As such, the patterns documented in Gale crater are consistent with reshaping of large portions of Mars by short-lived catastrophic events by wind and water, although data from other regions are needed to establish this on a planetary scale. The study is based on data collected by the Curiosity rover during the past 14 years. The aeolian event that excavated Gale crater was lithologically controlled. It formed two distinct morphological provinces with two contrasting rock types. One was the cone-shaped ancestral Aeolis Mons, informally known as Mt. Sharp, that consists of sandstone, siltstone, and mudstone. The other was the nearly flat hollowed margin, the ancestral crater floor, that was initially covered by loose pebbles, cobbles, and boulders which were reworked and lithified to a conglomeratic rock unit later. Commonly reported Martian aeolian erosion rates cannot account for the abrasion and transport of 39,000 km³ of sediments out of Gale crater. This conclusion is supported by little modification of Gale crater during the past 3.6 billion years by ordinary winds. Our evaluation indicates that the excavation of Gale crater took place by a powerful aeolian perturbation that resembled a sand-blasting operation. It was short-lived, had extremely high erosion rates, and occurred during a cold and dry climate. The fluvial episode followed the aeolian event. The study of its sedimentary record indicates that it began with intense precipitation-driven great floods that eroded the ancestral Mt. Sharp, carved large canyons on its slope, and reworked gravels of the ancestral crater floor into giant bedforms. Flood waters also formed a deep lake that experienced one rise and one fall of lake-level and had a dynamic storm-driven sedimentation. The fluvial episode was also short-lived and indicates catastrophic actions of water during a warm and wet climate. As such, this study suggests that the extensive reshaping of the red planet during the Late Noachian period, including formation of valley networks, occurrence of hundreds of crater lakes, and excavation of numerous craters, were also due to short-lived, intense, climate-related perturbations by powerful wind and water rather than by ordinary, slow rate, long-duration processes. Another implication of the study is for the mineralogical evolution of Martian sedimentary rocks. It indicates that the Late Noachian period may have been mostly cold and dry, similar to the modern Mars. Its low water/rock ratio and cold temperatures halted chemical weathering that resulted in preservation of highly unstable minerals such as olivine and pyroxene. The fluvial perturbation with its high water/rock ratio was not long and/or warm enough to alter or significantly affect the mineralogy by weathering at the source region, or during the transport, or at the depositional site. Full article

Aeolian sand bodies unrelated either to coastal barrier systems of Holocene or earlier age or to modern beaches have been identified along the central New South Wales coast of southeast Australia. Some of these deposits cap headlands or are located above high sea-cliffs. Others lie below modern sea-levels, whilst one substantial dune field extends 12 km inland. Many of these have previously been interpreted as Early Holocene cliff-top dunes, the product of the migration of beach sands up aeolian sand ramps at the foot of the sea-cliffs of the region and onto the cliff tops. The rising sea-levels of the Middle Holocene eroded the ramps and cut off the supply of sand to the dunes, allowing them to stabilise. But re-investigation shows that these dune fields accumulated at times of low Quaternary sea-levels, with a particle-size distribution suggestive of an inland rather than a coastal origin. We therefore propose an alternative model for the accumulation of these features. At times of low sea-level, sediments exposed on the inner-shelf were reworked onto the adjacent coast by onshore winds, where they accumulated in locations unconnected to the modern or the earlier Holocene coastal aeolian sedimentary regime. This model challenges the conventional story that the dominant glacial maximum winds across southeastern Australia were from the west (and thus offshore). This pattern of sediment accumulation and its associated wind regime may have been more stable (continuing for over 30 000 years) and more long-lived (repeated through at least the last two glacial cycles) than has previously been believed. Although the cliff-top dune model has been widely applied, we question its suitability in its type location and suggest a more cautious approach to its application elsewhere. We argue that the products of the landward aeolian reworking of sediment exposed on the continental shelf have been overlooked, despite their potential for the preservation of long-term environmental records. Full article

Supplementary cementitious materials and aeolian sand have been used to produce low-carbon ultra-high-performance concrete (UHPC) due to their beneficial effects on the reduction in production cost and carbon emissions. However, low-carbon UHPC still faces some drawbacks, such as lowered mechanical properties, large shrinkage, and a tendency for cracking. This study proposed an approach to improve the performance of low-carbon UHPC by incorporating recycled coarse aggregate. The effects of recycled coarse aggregate type, particle size, and content on the workability and mechanical properties of low-carbon UHPC were investigated. Moreover, the internal relative humidity and volume stability of UHPC containing recycled coarse aggregate was also explored. At last, the hydration products and microstructure of UHPC was analyzed to shed light on the underlying mechanisms for the improved performance. Full article

The scarcity of natural aggregates and the accumulation of oil sludge in desert regions pose critical challenges for highway construction. Although aeolian sand and oil sludge pyrolysis residue have been studied individually as construction materials, their combined use in foamed lightweight soil remains unexplored. This study addresses this gap by developing a novel foamed lightweight soil termed SOFS, which is created through the synergistic modification of aeolian sand and oil sludge pyrolysis residue. A six-factor, five-level orthogonal array (L25) was employed to systematically investigate the effects of residue content, sand content, foam-to-slurry ratio, foaming agent dilution, water-to-solid ratio, and mixing time. The evaluated properties included physical properties (fluidity and wet density), mechanical properties (compressive, splitting tensile, and flexural strength), and durability (wet–dry and freeze–thaw resistance). Scanning electron microscopy was used to examine the microstructural mechanisms. Variance and range analysis identified the optimal mixture, designated H14, which achieved 28-day compressive, splitting tensile, and flexural strengths of 3.75 MPa, 2.21 MPa, and 0.9 MPa, respectively, thereby meeting desert roadbed requirements. Compared with conventional materials, H14 exhibited superior durability, with strength losses of only 16.3% in compressive strength and 19.1% in splitting tensile strength after 25 cycles. Microstructural analysis revealed a dense C-S-H gel network encapsulating the solid waste particles, with nanoscale Al- and Cl-rich crystalline phases observed at interfacial pores—a phenomenon that has rarely been documented in previous studies. These findings provide a theoretical and technical foundation for solid waste valorization and the development of sustainable desert infrastructure. Full article